Just to clarify for the non-hackers out there: the point of having telnet isn't to be able to log in to other machines; nobody uses it for that any more.

The point of telnet is network debugging. There's nothing like "telnet foo 25" or "telnet foo 80" or even "telnet foo 22" for quickly finding out what's going on with your packets.

Netcat is an alternative, but an inferior one.